The Sandiganbayan Third Division denied motions filed by Enrile and his co-accused and former chief of staff, Gigi Reyes, for Tang to inhibit on questions of impartiality.

"After a rational and logical assessment of the circumstances in this case, the Court finds that there is no just or valid reason for the Chairperson to recuse herself from further hearing the case at bar," the court said in a resolution dated September 14.

Tang, who penned the resolution, chairs the anti-graft court's Third Division. Justices Sarah Jane Fernandez and Bernelito Fernandez also signed the resolution.

The third division is hearing graft and plunder cases against Enrile and Reyes, who are accused of diverting pork funds to bogus non-government organizations.

In his motion, Enrile said Tang is biased against him as she was appointed by former President Benigno Aquino III.

The presiding justice is influenced by "subconscious forces," which affects decisions she renders, Enrile said.

Reyes made the same arguments.

The court, however, said the mere imputation of bias is not enough ground for a judge to inhibit, and the allegation that Tang is subconsciously influenced by Aquino is sheer speculation.

"They have not shown adequate evidence to prove that the Chairperson's ponencias were influenced by former President Aquino III," the court said.

In his 2015 State of the Nation Address, Aquino said the indictment of officials involved in the pork barrel fund mess is an indication that his government's anti-corruption campaign spares no one.

Tang said if she allowed underlying powers to influence her decisions, she should have recused herself from the beginning because of the fact that she and Enrile are both from Cagayan.

She added that Enrile's lawyer, Estelito Mendoza, was also her mentor during her stint at the Office of the Solicitor General.

"From him, she learned much, gained much and grew much, in knowledge, in wisdom and in resolve," she wrote. "But the Chairperson took an oath before she donned her judicial robe — an oath she must discharge without fear or fervor; an oath she will not shrink from."

Enrile is currently out on bail while Reyes is detained at the BJMP facility in Taguig City.

They may file a motion for reconsideration on the ant-graft court's latest resolution.

Enrile, along with former Senators Bong Revilla and Jinggoy Estrada, were charged for the involvement in the pork barrel scandal.

The lawmakers were named by businesswoman Janet Lim Napoles, who is the alleged mastermind of the pork barrel scam unearthed by investigative media reports in July 2013.

An estimated P10 billion in government funds were allegedly lost from the scam, with the money being diverted to Napoles and lawmakers after projects were coursed through Napoles' company, JLN Corporation.